Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more turbine blades. The turbine blades capture kinetic energy from wind using known foil principles and transmit the kinetic energy through rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
To ensure that wind power remains a viable energy source, efforts have been made to increase energy outputs by modifying the size and capacity of wind turbines. One such modification has been to increase the length of the turbine blades. However, as is generally known, the deflection of a turbine blade is a function of blade length, aerodynamic loading, turbine operating states and blade stiffness. Thus, longer turbine blades may be subject to increased deflection forces, particularly when a wind turbine is operating in high-load conditions. This increased deflection can produce fatigue on the turbine blades and other components and can also increase the risk of the turbine blades striking the tower. A tower strike can significantly damage a turbine blade and the tower and, in some instances, can cause catastrophic failures. Accordingly, a tower strike may result in considerable downtime to repair or replace damaged components.
Known wind turbine systems determine turbine blade deflection by utilizing external sensors, which are typically mounted on the turbine blades or on the tower. These sensors are designed to sense turbine blade operating conditions (e.g. blade strain, blade acceleration or blade velocity) to enable blade deflection to be inferred or calculated. However, maintaining the sensors can be very costly and calibrating such sensors can be quite complex and time consuming. Moreover, since the sensors must be calibrated frequently, there is a concern with regard to the reliability of data transmitted from the sensors over an extended period of time.
Accordingly, there is a need for an improved system and method for monitoring and controlling wind turbine blade deflection that prevents blade tower strikes without the excessive complexity and costs of the aforementioned sensors.